The invention relates to a front structure of an aircraft fuselage comprising landing gear.
Usually the front landing gear on an aircraft is housed in a gear housing situated inside the front structure of the fuselage. This housing performs a dual function depending on whether the aircraft is in flight or on the ground.
During flight, the housing isolates the gear from the aerodynamic flows so as to increase the performance of the aircraft.
On the ground, its role is to transmit the forces induced by the landing gear to the reinforcing elements of the front structure, in particular its frames.
Currently, the elements that form the landing gear are connected to the frames of the front structure by means of the elements of the landing-gear housing.
FIG. 1 illustrates a portion of an aircraft fuselage 1 of the prior art, more particularly a conventional aircraft front structure 2.
The front structure 2 most frequently consists of frames and an outer skin which are interrupted by apertures designed for the installation of cockpit windows 3.
This structure comprises a landing-gear housing 4, of substantially parallelepipedal shape, comprising a hatch 6, two side walls 8, a ceiling 9, a front wall 10 and a rear wall 12.
The hatch 6, consisting of two substantially rectangular articulated flaps, is situated flush with the front structure 2 and locally closely follows the curvature thereof. In the closed position, it is locally substantially flat.
On either side of this hatch 6 there are two side walls 8 that are substantially flat and parallel with one another which connect the hatch 6 and the ceiling 9 which is substantially flat and has a rectangular surface.
The landing-gear housing 4 is closed at the front (toward the front of the fuselage) by the front wall 10 which extends from the hatch 6 to the ceiling 9 and, at the rear, by the rear wall 12 that is substantially flat and perpendicular to the hatch 6.
A conventional landing gear 20 incorporated into the landing-gear housing 4 is shown in FIG. 2.
Such a gear notably comprises a leg 22 furnished at one end with wheels 24 and, at a distance from this end, a strut 26 taking the form of a Y.
The leg 22 is connected at its end opposite to the wheels 24 to a shaft 28, called the main shaft. This main shaft 28 has the same direction as the pitch axis of the aircraft. The shaft 28 is connected at each of its opposite ends to one of the side walls 8 close to the junction between the rear wall 12 and the hatch 6.
The strut 26, for its part, is connected at its end closest to the wheels (the base of the Y) to the leg 22, and at its other two opposite ends (the branches of the Y) to a shaft 29, called the stay shaft. This stay shaft 29 is parallel with the main shaft 28. It is connected at each of its opposite ends to one of the side walls 8, close to the ceiling 9 and approximately halfway between the front wall 10 and the rear wall 12.
The main shaft 28 and the stay shaft 29 are used to cause the leg 22 and the strut 26 to pivot about the pitch axis of the aircraft so as to move the landing gear 20 from a deployed position such as that of FIG. 2 to a retracted position in which the gear is confined in substantially horizontal position (the horizontal position of the aircraft when it is on the ground) inside the housing 4.
When the aircraft is running on the ground, it is therefore to the bearings of the main shaft 28 and stay shaft 29 that the axial forces coming from the wheels 24 are transmitted.
Since these bearings are connected to the walls 8 of the landing-gear housing 4, it is the walls that transmit the forces induced by the landing gear 20 to the front structure 2.